Imprint device and microstructure transfer method

ABSTRACT

There is provided an imprint device for transferring a fine pattern to a material to form a patterned material. The device comprises a stamper having the fine pattern thereon, and a pressure distribution mechanism. The stamper is pressed against the material, and the pressure distribution mechanism provides a nonuniform pressure distribution in a patterned region of the patterned material, while the stamper is in contact with the material. There are provided an imprint device and a microstructure transfer method, by which it is possible to sufficiently spread a resin or other material for forming a pattern layer between a stamper and a patterned material with a lower pressure so as not to damage the stamper or the patterned material, and to form a pattern formation layer having the uniform thickness on the patterned material.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. application Ser.No. 11/774,244, filed Jul. 6, 2007, the contents of which areincorporated herein by reference.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the foreign priority benefit under Title 35,United States Code, §119 (a)-(d), of Japanese Patent Application No.2006-187958 filed on Jul. 7, 2006 in the Japan Patent Office, thedisclosure of which is herein incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an imprint device and a microstructuretransfer method for transferring a fine-patterned structure of a stamperto a surface of a patterned material.

2. Description of the Related Art

Microfabrication of semiconductor integrated circuits has progressed andthere has been improvement in the accuracy for forming a pattern of asemiconductor integrated circuit by, for example, the photolithographydevice in order to perform the microfabrication process. On the otherhand, a pattern for the microfabrication process is almost as small as awavelength of an exposure light source, and therefore themicrofabrication process is approaching to a limit for the high accuracyof the pattern formation. Therefore, the electron beam lithographydevice, which is a type of the charged particle beam device, has beenused instead of the photolithography device in order to obtain thehigher accuracy of the pattern formation.

The pattern formation by the electron beam lithography device isdifferent from a pattern formation by a batch exposure method using alight source such as i-line, an excimer laser or the like, and in theelectron beam lithography device an exposure (drawing) time of patternsincreases according to the increasing of the patterns to be drawn by theelectron beam. Therefore, the time required for the pattern formationbecomes longer as the integration of the semiconductor integratedcircuit increases. As a result, a throughput becomes considerably lower.

For speeding up the pattern formation by the electron beam lithographydevice, there has been development in batch drawing radiation method, inwhich the electron beam is applied with various types of masks combined.However, the electron beam lithography device, which uses the batchdrawing radiation method, increases in size and requires a mechanism forcontrolling a position of a mask with higher accuracy, therebyincreasing the cost of the device.

Furthermore, there has been known as another technique for the patternformation an imprint technique for transferring a surface structure of apredetermined stamper on a patterned material by pressing the stamperagainst the patterned material. In the imprint technique, the stamperhas a fine-patterned portion (surface structure) corresponding to afine-patterned portion of a pattern to be formed on the patternedmaterial. The stamper is pressed against the patterned material, whichis produced by forming a resin layer on a prescribed substrate. Thereby,a microstructure having a fine pattern width of less than or equal to 25nm is transferred to and formed on the resin layer of the patternedmaterial. The resin layer having the pattern transferred thereto(hereinafter referred to as a pattern formation layer) includes a thinfilm layer formed on a substrate and a pattern layer formed on the thinfilm layer and having projections. There has been consideration forapplications of the imprint technique in the pattern formation for arecord bit in a high-capacity recording medium or a semiconductorintegrated circuit. For example, a substrate for a high-capacityrecording medium or a semiconductor integrated circuit may bemanufactured by etching an exposed portion of a thin film layer at aconcave portion of the pattern formation layer, and a portion of asubstrate in contact with the portion of the thin film layer with aconvex portion of the pattern formation layer formed by the imprinttechnique as a mask. The accuracy for the etching process of thesubstrate is affected by a thickness distribution of the thin film layerin the surface direction. More specifically, for example, a thicknessvariation of the thin film layer in the surface direction is such thatthe difference in thickness between the thickest portion and thethinnest portion of the thin film layer is 50 nm. When the patternedmaterial having such a thin film layer is etched in the depth of 50 nm,the substrate in contact with the thin portion of the thin film layer isetched while the substrate in contact with the thick portion of the thinfilm layer may not be etched. Therefore, the thickness of the thin filmlayer formed on the substrate needs to be uniform in order to maintain apredefined accuracy of the etching process. Namely, the thickness of theresin layer formed on the substrate needs to be uniform in the surfacedirection in order to form the thin film layer having the uniformthickness.

U.S. Pat. No. 6,696,220 discloses a conventional imprint deviceincluding a stamper having a flat surface on which a fine pattern isformed, and the flat surface of the stamper is mechanically pressedagainst the patterned material, thereby transferring the fine pattern tothe patterned material. In the imprint device, the fine pattern isformed on the flat surface of the stamper, and therefore it is possibleto apply a uniform pressure to a patterned region, to which the finepattern of the stamper is transferred, of the patterned material. Whenthe uniform pressure is applied to the patterned region, the resin layerhaving the uniform thickness is formed on the patterned material. Thatis, when the fine pattern is formed on the patterned material with theresin layer having the uniform thickness, the thickness of the patternformation layer is uniform and thereby the thickness of the thin filmlayer of the pattern formation layer is uniform, too.

However, the above-described imprint device requires an adjustmentmechanism capable of aligning the stamper and the patterned materialparallel to each other with high accuracy, thereby making aconfiguration of the imprint device complicated. Furthermore, in theimprint device, there is a limit on the size of the stamper to be ableto be made flat, and it is difficult to form the pattern formation layer(thin film layer) having the uniform thickness by pressing a larger sizeof the patterned region against the stamper at one time.

For example, Japanese Laid-open Patent Application Nos. 2003-157520 and2005-52841 disclose an imprint device, in which a patterned material anda stamper are pressed against each other on a stage through an elasticmaterial. United States Patent Publication No. 2003/189273 discloses animprint device in which a liquid is sealed in a cavity provided on aback surface of a stamper or a patterned material. Furthermore, U.S.Pat. No. 6,482,742 discloses an imprint device in which a stamper and apatterned material are disposed within a vessel, the internal pressureof which is adjusted.

In the imprint devices of the above-described patent references,however, a pressure distribution between the surfaces of the stamper andthe patterned material is uniform when the stamper and the patternedmaterial are pressed against each other. Therefore, it is difficult tosufficiently spread the resin between the stamper and the patternedmaterial when the patterned region is larger and the thin film layer isthinner. In this case, the stamper and the patterned material can bedamaged when the stamper is pressed against the patterned material witha higher pressure to spread the resin between the stamper and thepatterned material.

SUMMARY OF THE INVENTION

The present invention was made to solve the problems as described above,and it is an object of the present invention to provide an imprintdevice and a microstructure transfer method, by which it is possible tosufficiently spread a resin or other material for forming a patternlayer between a stamper and a patterned material with a lower pressureso as not to damage the stamper or the patterned material, and to form apattern formation layer having the uniform thickness on the patternedmaterial.

According to one aspect of the present invention, there is provided animprint device for transferring a fine pattern to a material to form apatterned material. The device comprises a stamper having the finepattern thereon, and a pressure distribution mechanism. The stamper ispressed against the material, and the pressure distribution mechanismprovides a nonuniform pressure distribution in a patterned region of thepatterned material, while the stamper is in contact with the material.

According to another aspect of the present invention, there is provideda microstructure transfer method comprising a step of contacting astamper having a fine pattern thereon with a material, and a step oftransferring the fine pattern of the stamper to the material by pressingthe stamper against the material, so as to form a patterned material. Inthe step of transferring, a nonuniform pressure distribution is providedin a patterned region of the patterned material.

With the imprint device and the microstructure transfer method of thepresent invention, it is possible to sufficiently spread a resin orother material for forming a pattern layer between a stamper and apatterned material with a lower pressure so as not to damage the stamperor the patterned material, and to form a pattern formation layer havingthe uniform thickness on the patterned material.

BRIEF DESCRIPTION OF THE DRAWINGS

The object and features of the present invention will become morereadily apparent from the following detailed description taken inconjunction with the accompanying drawings in which:

FIG. 1 illustrates a configuration of an imprint device according to afirst embodiment of the present invention;

FIGS. 2A to 2D schematically illustrate a process of a microstructuretransfer method according to an embodiment of the present invention;

FIGS. 3A and 3B illustrate an imprint device according to a secondembodiment of the present invention, FIG. 3A illustrates a configurationof an imprint device, and FIG. 3B schematically illustrates anarrangement of openings of flow paths provided in an imprint device;

FIG. 4 illustrates a configuration of an imprint device used in a firstexample of the present invention;

FIG. 5 illustrates a configuration of an imprint device used in a thirdexample of the present invention;

FIG. 6 illustrates a configuration of an imprint device used in a fourthexample of the present invention;

FIG. 7 is an electron microscope photograph showing a cross-sectionalsurface of a pattern formation layer having a thin film layer and apattern layer;

FIGS. 8A to 8D illustrate a manufacturing process of a discrete trackmedium;

FIGS. 9A to 9E illustrate a manufacturing process of a discrete trackmedium;

FIGS. 10A to 10E illustrate a manufacturing process of a disk substratefor a discrete track medium;

FIGS. 11A to 11E illustrate a manufacturing process of a disk substratefor a discrete track medium;

FIG. 12 is a schematic block diagram of an optical circuit as a basiccomponent of an optical device;

FIG. 13 is a schematic block diagram of a structure of a waveguide of anoptical circuit; and

FIGS. 14A to 14L illustrate a process of manufacturing a multilayerinterconnection substrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, embodiments of the present invention will be described indetail with reference to the attached drawings.

First Embodiment

Detailed description will be provided for a first embodiment of thepresent invention with reference to the attached drawings. FIG. 1illustrates a configuration of an imprint device according to the firstembodiment.

As shown in FIG. 1, an imprint device A1 of the first embodimentincludes an up-down mechanism 11, a stage 5 that is moved up and down bythe up-down mechanism 11, a plate 3, and a buffer layer 7. The plate 3and the buffer layer 7 are disposed on the stage 5 in order. The imprintdevice A1 includes air intake paths E connected to a suction unit (notshown) such as a pump. Each of the air intake paths E passes through theinside of the up-down mechanism 11, the stage 5, the plate 3, and thebuffer layer 7, and has an opening at the upper surface of the bufferlayer 7. An opening of the air intake path E on the opposite side of thebuffer layer 7 is connected to the above-described suction unit. Apatterned material 1 is disposed on the plate 3 through the buffer layer7, and a stamper 2 is arranged above the patterned material 1. Photocurable resin 6 (see FIG. 2A), which will be described later, is appliedto the surface of the patterned material 1 opposing the stamper 2. Afine pattern 2 a (see FIG. 2A) having a fine-patterned structure isformed on the surface of the stamper 2 opposing the patterned material1. As shown in FIG. 1, the stamper 2 is held by a stamper holding unit4, and the patterned material 1 is pressed against the stamper 2 bymoving up the stage 5 by the up-down mechanism 11. The stage 5 isdisposed in a space of a pressure-reduced chamber, and it is possible toreduce the pressure in the pressure-reduced chamber by an exhaust unit(not shown) such as a vacuum pump. The above-described imprint device A1is designed to transfer the fine pattern 2 a of the stamper 2 to asurface of the patterned material 1 by pressing the stamper 2 againstthe patterned material 1, and to provide a nonuniform pressuredistribution in a patterned region on the surface of the patternedmaterial 1 having the fine pattern 2 a is transferred.

It should be noted that the patterned material 1 denotes a materialhaving the fine pattern 2 a of the stamper 2 transferred thereto andalso a material before the fine pattern 2 a of a stamper 2 istransferred. In the following description, for convenience ofexplanation, the material before and after the fine pattern 2 a of thestamper 2 is transferred to the material will be referred to as thepatterned material 1.

The plate 3 may be made of glass, metal, resin, or the like. The plate 3is harder and has a higher coefficient of elasticity than that of thebuffer layer 7, which will be described below, and the plate 3 has thestrength and the capacity to be provided with a desired curved surface.The plate 3 has a curved surface C on the upper side thereof, and isdisposed on the stage 5 so that the highest portion of the curvedsurface C is positioned in the center. The curved surface C of the plate3 may be a spherical surface having the constant curvature, or anaspheric (crooked) surface, that is, a curvature in a region, to whichthe fine pattern 2 a of the stamper 2 is transferred (hereinafterreferred to as a patterned region), is larger than a curvature in aregion outside the patterned region. The plate 3 may have anyappropriate surface structure to provide a required pressuredistribution for forming a predetermined thin film layer T1 (see FIG.2D), which will be described later. The highest portion of the plate 3may not be positioned only in the center portion of the patternedregion, but may be positioned, for example, in portions other than thecenter portion. The plate 3 may be configured such that the highestportion of the plate 3 is formed like peaks so as to define aring-shaped closed region.

The buffer layer 7 is an elastic layer formed on the curved surface C ofthe plate 3. The buffer layer 7 is made of a material having a lowercoefficient of elasticity than that of a material of the plate 3, thepatterned material 1, or the stamper 2. The patterned material 1 and thestamper 2 will be described later in detail. The buffer layer 7 havingsuch a lower coefficient of elasticity prevents a position of thepatterned material 1 from being moved relative to the stamper 2 when thestamper 2 is pressed against the patterned material 1.

A material or a thickness of the buffer layer 7 may be appropriatelydetermined to provide a required pressure distribution for forming thethin film layer T1 (see FIG. 2D), which will be described later. Thebuffer layer 7 may be made of resin such as polystyrene, polyamide, orpolycarbonate, or silicone resin. The buffer layer 7 may include amaterial such as fluorine to enhance separation of a material from thebuffer layer 7, or a layer including a material to enhance theseparation may be formed on a surface of the buffer layer 7. The uppersurface of the buffer layer 7 corresponds to the curved surface C of theplate 3.

The patterned material 1 is a disk-shaped member, and the fine pattern 2a formed on the stamper 2 is transferred to the patterned material 1.The patterned material 1 of the first embodiment includes a substrate 10(see FIG. 2A) and the photo curable resin 6 (see FIG. 2A) applied to thesubstrate 10 so as to form a pattern formation layer T3 (see FIG. 2D) onthe substrate 10, as described below. The substrate 10 and the patternformation layer T3 will be later described in detail. The photo curableresin 6 may be a well-known resin material having a photosensitivematerial added thereto. The photo curable resin 6 may be a resinmaterial including cyclo-olefin polymer, polymethyl methacrylate,polystyrene polycarbonate, polyethylene terephthalate (PET),polylactate, polypropylene, polyethylene, polyvinyl alcohol, or the likeas a dominant component.

The photo curable resin 6 may be applied to the substrate 10 by thedispensing technique or the spin coating technique.

When using the dispensing technique, the photo curable resin 6 isdropped to the surface of the substrate 10. The dropped photo curableresin 6 spreads on the surface of the substrate 10 when the stamper 2 ispressed against the patterned material 1. When the photo curable resin 6is dropped to a plurality of positions on the substrate 10, a distancebetween each of the centers of the positions may be made longer than thediameter of a drop of the photo curable resin 6.

In order to determine a position where the photo curable resin 6 isdropped, the spread of the photo curable resin 6 may be estimateddepending on a fine pattern to be formed. Then, the position where thephoto curable resin 6 is dropped is determined depending on theestimation. An amount of the photo curable resin 6 per drop onto thesubstrate 10 is adjusted to be at least the necessary amount to form thethin film layer T1 (see FIG. 2D) and a pattern layer T2 (see FIG. 2D)formed on the surface of the thin film layer T1, and a position of eachdrop of the photo curable resin 6 is adjusted at the same time. The thinfilm layer T1 and the pattern layer T2 will be described in detaillater.

When using the spin coating technique, an amount of the photo curableresin 6 per drop onto the substrate 10 is adjusted to be at least thenecessary amount to form the thin film layer T1 (see FIG. 2D) and apattern layer T2 (see FIG. 2D) formed on the surface of the thin filmlayer T1. Also, a spin rotation speed and a viscosity of the photocurable resin 6 are adjusted at the same time.

An applicable material to the patterned material 1 used in the presentinvention, other than the photo curable resin 6, includes one having athin film of resin other than the photo curable resin 6, such asthermosetting resin or thermoplastic resin, formed on the prescribedsubstrate 10, or one made of such a resin (including a resin sheet)alone. When using the thermoplastic resin, the patterned material 1 isprepared to have a temperature higher or equal to the glass transitiontemperature of the thermoplastic resin before the stamper 2 is pressedagainst the patterned material 1. When using the thermoplastic resin,the patterned material 1 and the stamper 2 are cooled off after thestamper 2 is pressed against the patterned material 1. When using thethermosetting resin, the patterned material 1 and the stamper 2 are leftat a polymerization temperature after the stamper 2 is pressed againstthe patterned material 1, thereby curing the thermosetting resin. Afterthe thermosetting resin or the thermoplastic resin becomes cured, thepatterned material 1 and the stamper 2 are separated from each other,whereby the fine pattern 2 a of the stamper 2 is transferred to thepatterned material 1.

A material of the above-described substrate 10 may be chosen fromvarious types of materials, such as silicon, glass, aluminum alloy, orresin. The substrate 10 may have a multilayer structure where a metallayer, a resin layer, an oxide film layer or the like is formed on thesurface of the substrate 10.

An outline of the patterned material 1 may be a circle, an ellipse, or apolygon according to an application thereof, and the patterned material1 may be provided with a center through hole.

As described above, the stamper 2 has the fine pattern 2 a to betransferred to the patterned material 1. A fine-patterned portion of thefine pattern 2 a is formed on the surface of the stamper 2 by, forexample, the photolithography technique, the focused ion beamlithography, the electron-beam printing technique, the platingtechnique, or the like. An appropriate technique to form the finepattern 2 a on the stamper 2 may be determined depending on an accuracyof processing of the fine pattern 2 a to be formed. In the firstembodiment, the stamper 2 is made of a transparent material because thephoto curable resin 6 applied to the patterned material 1 is irradiatedwith an electromagnetic ray such as an ultraviolet light through thestamper 2. However, the present invention is not limited to this, andthe stamper 2 may also be an opaque material when other material such asthermosetting resin or thermoplastic resin is used instead of the photocurable resin 6.

A material of the stamper 2 may be silicon, glass, nickel, resin, or thelike. An outline of the stamper 2 may be a circle, an ellipse, or apolygon depending on a technique of pressing the stamper 2. The stamper2 may be provided with a center through-hole. Furthermore, afluorine-based or silicone-based release agent may be applied to thesurface of the stamper 2 in order to smoothly separate the photo curableresin 6 and the stamper 2. The stamper 2 may have different shape andsurface area from the patterned material 1 as long as the fine pattern 2a is transferred to a predetermined region of the patterned material 1.

With reference to the attached drawings, description will be providedfor an operation of the imprint device A1 and a microstructure transfermethod according to the first embodiment. Of the drawings to be referredto, FIGS. 2A to 2D schematically illustrate a process of amicrostructure transfer method according to an embodiment of the presentinvention, and mainly illustrate positional relations between thestamper 2 and the patterned material 1.

In the imprint device A1 shown in FIG. 1, the patterned material 1 isarranged on the plate 3 through the buffer layer 7. Specifically, thepatterned material 1 is disposed on the curved upper surface of thebuffer layer 7 having the highest portion of the curved surface in thecenter. The patterned material 1 is vacuumed onto the upper surface ofthe buffer layer 7 through the openings of the air intake paths E sothat the patterned material 1 is supported on the buffer layer 7. Then,as described above, the air is discharged from the pressure-reducedchamber, and thereby the patterned material 1 is exposed to apressure-reduced atmosphere in the pressure-reduced chamber.

When the stage 5 is then moved up by the up-down mechanism 11 shown inFIG. 1, the stamper 2 is pressed against the patterned material 1.Accordingly, as shown in FIG. 2B, the photo curable resin 6 applied tothe patterned material 1 contacts the fine pattern 2 a (see FIG. 2A) ofthe stamper 2. Because the lower surface of the patterned material 1 isin contact with the buffer layer 7 having the highest portion in thecenter, the upper surface of the patterned material 1 is pressed againstthe stamper 2 with the highest pressure at the center portion of thepatterned material 1. As the stage 5 is further moved up, the pressureapplied to the patterned material 1 increases, so that the pressuredistribution on the patterned material 1 changes over time.

Because the buffer layer 7 has the curved surface, the pressure appliedto the patterned material 1 gradually becomes lower from the centerportion toward the circumference portion thereof. That is, the pressuredistribution on the patterned material 1 is nonuniform. As the stage 5is further moved up, the pressure distribution on the patterned material1 changes over time from the center portion toward the circumferenceportion thereof. The elastic buffer layer 7 is more greatly deformed inthe center portion thereof, and is less deformed toward the outercircumference of the patterned material 1. As a result, the pressureapplied to the patterned material 1 becomes highest in the centerportion thereof, gradually becomes lower toward the circumferenceportion, and becomes lowest at the outermost circumference thereof.Namely, a contour line of the pressure distribution is defined in aconcentric pattern on the patterned material 1. As described above, thephoto curable resin 6 applied to the patterned material 1 spreadsbetween the stamper 2 and the patterned material 1 when the stamper 2 ispressed against the patterned material 1.

Preferably, an alignment mechanism (not shown) is provided to align thestamper 2 with the patterned material 1 when the stamper 2 contacts thepatterned material 1. An alignment technique may be a mechanicaltechnique, by which the patterned material 1 and the stamper 2 arephysically placed on a base component, or an optical technique, by whicha predetermined reference point provided on each of the patternedmaterial 1 and the stamper 2 is optically detected. An appropriatealignment technique may be chosen depending on a shape of the concernedpatterned material 1 or a required accuracy of the alignment, or thelike. The alignment of the stamper 2 and the patterned material 1 iscarried out before the photo curable resin 6 becomes cured and may becarried out before or after the patterned material 1 contacts thestamper 2.

As shown in FIG. 2C, the photo curable resin 6 is irradiated with anultraviolet light UV from a light source (not shown) through the stamper2 so that the photo curable resin 6 becomes cured. When the stage 5 ismoved down by the up-down mechanism 11 shown in FIG. 1, the patternedmaterial 1, which is vacuumed onto the upper surface of the buffer layer7 through the openings of the air intake paths E, is separated from thestamper 2. Accordingly, as shown in FIG. 2D, the patterned material 1separated from the stamper 2 has the fine pattern 2 a of the stamper 2transferred thereto. Therefore, the patterned material 1 has the patternformation layer T3 formed on the substrate 10. The pattern formationlayer T3 includes the thin film layer T1 as a base layer and the patternlayer T2 formed on the thin film layer T1 and having projections.

According to the imprint device A1 and the microstructure transfermethod as described above, the pressure distribution provided betweenthe stamper 2 and the patterned material 1 is nonuniform, unlike theconventional imprint device or the conventional transfer method asdisclosed in, for example, the above-described patent references.According to the imprint device A1 and the microstructure transfermethod, it is possible to spread the photo curable resin 6 between thestamper 2 and the patterned material 1 with a low pressure so as not todamage the stamper 2 or the patterned material 1, even when it is aimedto enlarge a patterned region or reduce the thin film layer T1 in thethickness. It is also possible to form the pattern formation layer T3having a uniform thickness on the patterned material 1.

Second Embodiment

Next, detailed description will be provided for a second embodiment ofthe present invention with reference to the attached drawings. Of thedrawings to be referred to, FIGS. 3A and 3B illustrate an imprint deviceaccording to the second embodiment. FIG. 3A illustrates a configurationof an imprint device, and FIG. 3B schematically illustrates anarrangement of openings of flow paths provided in an imprint device. Inthe imprint device according to the second embodiment, a configurationof a plate arranged on a stage is different from that of the plateaccording to the first embodiment, and therefore description will bemainly provided for the configuration of the plate of the secondembodiment.

In an imprint device A2 of the second embodiment, as shown in FIG. 3A, aplate 3 has the flat upper surface on the side to face the stamper 2. Abuffer layer 7 is disposed on the flat upper surface of the plate 3, andthe buffer layer 7 also has a flat upper surface. The imprint device A2includes a plurality of flow paths H, through which pressurized fluidflows. Each of the plurality of flow paths H passes through the insideof an up-down mechanism 11, a stage 5, the plate 3, and the buffer layer7, and has an opening at the upper surface of the buffer layer 7.

As shown in FIG. 3B, the openings of the flow paths H are arranged infive concentric circles on the upper surface of the buffer layer 7. Theflow paths H, the openings of which are arranged in the same circle, areconnected to the same pipe, respectively. More specifically, the flowpaths H, the openings of which are arranged in the innermost circle onthe upper surface of the buffer layer 7, are connected to a ring-shapedpipe P1, as shown in FIG. 3B. Furthermore, the other flow paths Harranged in other outer circles, from the inside toward the outside ofthe upper surface of the buffer layer 7, are connected to ring-shapedpipes P2, P3, P4, and P5 in series. Although not shown, the pipes P1,P2, P3, P4, and P5 are disposed inside the up-down mechanism 11 (seeFIG. 3A). As shown in FIG. 3B, the pipes P1, P2, P3, P4, and P5 areconnected to pressure adjustment mechanisms B1, B2, B3, B4, and B5,respectively, which adjust the pressure of fluid flowing through each ofthe pipes P1, P2, P3, P4, and P5. The pressure adjustment mechanisms B1,B2, B3, B4, and B5 adjust the pressure of fluid flowing through each ofthe pipes P1, P2, P3, P4, and P5, so that the fluid is ejected from theopenings of the flow paths H arranged in the same circle with the samepressure. The pressure with which the fluid is ejected from the openingsmay not necessarily be the same, and may be adjusted to a differentpressure if required.

Next, description will be provided for an operation of the imprintdevice A2 and a microstructure transfer method according to the secondembodiment.

In the above-described imprint device A2, the stage 5 is moved up by theup-down mechanism 11 shown in FIG. 3A, and the fluid is ejected fromeach of the openings of the flow paths H provided on the buffer layer 7.Thereby, the lower surface of the patterned material 1 is separated fromthe upper surface of the buffer layer 7 and then the upper surface ofthe patterned material 1 contacts the stamper 2. The fluid is ejectedfrom the openings of the flow paths H connected to the pipe P1 arrangedon the innermost side, and then the fluid is ejected from the openingsof the flow paths H connected to the pipes P2, P3, P4, and P5 in series.Thereby, the pressure distribution on the patterned material 1 changesover time from the center portion toward the outer circumferentialportion thereof. Furthermore, the pressure of the fluid flowing througheach of the pipes P1, P2, P3, P4, and P5 is adjusted such that thepressure of the fluid through the pipe P1 is highest and the pressure ofthe fluid through each of the pipes P2, P3, P4, and P5 gradually becomeslower, so that the center portion of the upper surface of the patternedmaterial 1 is pressed against the stamper 2 with the highest pressure,and the pressure applied to the patterned material 1 gradually becomeslower from the center portion of the patterned material 1 toward thecircumferential portion thereof. The elastic buffer layer 7 is moregreatly deformed in the center portion thereof, and is less deformedtoward the outer circumference of the patterned material 1. As a result,the pressure applied to the patterned material 1 is highest in thecenter portion thereof, gradually becomes lower toward the circumferenceportion, and is lowest at the outermost circumference thereof. Morespecifically, a contour line of the pressure distribution is defined ina concentric pattern on the patterned material 1. The photo curableresin 6 applied to the patterned material 1 spreads between the stamper2 and the patterned material 1 when the stamper 2 is pressed against thepatterned material 1 as described above. The fluids may be ejectedthrough the pipes P1, P2, P3, P4, and P5 simultaneously without changingthe timing for ejecting the fluid through each of the pipes P1, P2, P3,P4, and P5, as described above. In this case, it is preferable to changethe pressure of the fluid through each of the pipes P1, P2, P3, P4, andP5 so as to provide the pressure distribution on the patterned material1.

Then, after the photo curable resin 6 becomes cured in the same manneras that of the first embodiment, the pressure of the fluid through eachof the pipes P1, P2, P3, P4, and P5 is reduced by the pressureadjustment mechanisms B1, B2, B3, B4, and B5 so that the patternedmaterial 1 sticks to the upper surface of the buffer layer 7. Next, thestage 5 is moved down by the up-down mechanism 11 shown in FIG. 3A, andthereby the patterned material 1 is separated from the stamper 2.Accordingly, the separated patterned material 1 has the patternformation layer T3 formed on the substrate 10 and having the finepattern 2 b (see FIG. 2D) of the stamper 2 transferred thereto.

According to the imprint device A2 and the microstructure transfermethod as described above, the pressure distribution provided betweenthe stamper 2 and the patterned material 1 is nonuniform, unlike theconventional imprint devices and the transfer methods as disclosed in,for example, the above-described patent references. According to theimprint device A2 and the microstructure transfer method, it is possibleto spread the photo curable resin 6 between the stamper 2 and thepatterned material 1 with a low pressure so as not to damage the stamper2 or the patterned material 1, even when a patterned region is enlargedand the thin film layer T1 is reduced in the thickness. It is alsopossible to form the pattern formation layer T3 having the uniformthickness on the patterned material 1.

The present invention is not limited the configurations of theabove-described embodiments, and may have other various configurations.

According to the above embodiments, the fine pattern 2 a is transferredto one side of the patterned material 1. However, the fine pattern 2 amay be transferred to both sides of the patterned material 1. In thiscase, a pair of stampers 2, 2 is arranged to sandwich the patternedmaterial 1.

According to the above-mentioned first embodiment, the stamper 2 ispressed against the patterned material 1 in a pressure-reducedatmosphere. In the present invention, however, the stamper 2 may bepressed against the patterned material 1 in atmospheric pressure.

In the above embodiments, after the stamper 2 is arranged above theplate 3, the patterned material 1 having the photo curable resin 6applied thereto is arranged to face the stamper 2. However, an imprintdevice according to the present invention may be configured such thatthe patterned material 1 having the photo curable resin 6 appliedthereto is arranged on the plate 3 and then the stamper 2 is arranged toface the patterned material 1. Furthermore, the stamper 2 having thephoto curable resin 6 applied thereto may be arranged relative to thepatterned material 1 in the same manner as described above. The imprintdevices A1, A2 according to the above-described embodiments may beconfigured such that a unit for applying the photo curable resin 6, suchas a dispenser or an inkjet head, is mounted in the devices A1, A2 sothat the photo curable resin 6 is automatically applied to the patternedmaterial 1 or the stamper 2.

In the first embodiment of the present invention, the patterned material1 is pressed against the stamper 2 held by the stamper holding unit 4 bymoving up the stage 5. In the present invention, however, the stamper 2may be arranged between the patterned material 1 and an upper plate 3 bheld by a plate holding unit 3 c, as shown in FIG. 4, so that thepatterned material 1 is pressed against the stamper 2 by moving up thestage 5. On a surface of the upper plate 3 b opposing the stamper 2 maybe arranged a buffer layer 7 similar to the buffer layer 7 arranged onthe surface of the plate 3. The upper plate 3 b may be provided with acurved surface C on the side to face the patterned material 1 in thesame manner as the curved surface C of the plate 3. The imprint deviceshown in FIG. 4 will be described in a first example in detail later.

In the second embodiment of the present invention, the plurality of flowpaths H is provided in the plate 3. In an imprint device including theabove-described upper plate 3 b (see FIG. 4), a plurality of flow pathsH may be provided in the upper plate 3 b. More specifically, when theupper plate 3 b is pressed against the stamper 2, a fluid ejects througheach of the flow path H provided in the upper plate 3 b, so that acontour line of the pressure distribution is defined in a concentricpattern on the stamper 2 from the center portion toward thecircumference portion thereof, in the same manner as the patternedmaterial 1 in the second embodiment.

The patterned material 1 having the fine pattern 2 a transferred theretoaccording to the first and second embodiments may be applied to aninformation recording medium such as a magnetic recording medium or anoptical recording medium. Furthermore, the patterned material 1 may beapplied to a component for a large-scale integrated circuit, an opticalcomponent such as a lens, a polarization plate, a wavelength filter, alight emitting device, or an optical integrated circuit, or a bio-devicefor immune assay, DNA separation, cell culture, or the like.

Example

Next, the present invention will be described in more detail byillustrating examples of the present invention.

First Example

In a first example, description will be provided for a microstructuretransfer method of transferring a fine pattern of a stamper 2 to apatterned material 1 by using an imprint device A3 shown in FIG. 4. FIG.4 illustrates a configuration of an imprint device used in the firstexample.

In the imprint device A3 shown in FIG. 4, a plate 3 having a curvedsurface on one side was arranged on a stage 5, which was made ofstainless steel and was configured to move up and down. The plate 3 wasmade of quartz. The plate 3 was 30 mm in diameter, 10 mm in thickness atmaximum, and had a spherical surface having the curvature radius of 2595mm. A silicone rubber layer having the thickness of 0.5 mm was disposedon the surface of the plate 3 so as to form a buffer layer 7 on theplate 3. On the buffer layer 7 were disposed a patterned material 1,stamper 2, and a spacer S in this order. The patterned material 1 andthe stamper 2 were arranged such that a resin-applied surface of thepatterned material 1 and a pattern-formed surface of the stamper 2 werefaced to each other. An upper plate 3 b was held by a plate holding unit3 c above the spacer S. The upper plate 3 b was made of quartz.

A pin L1 was inserted through central through-holes of the stage 5 andthe plate 3 so as to align the axes of the central through-holes of thepatterned material 1 and the stamper 2. Although not shown in FIG. 4, apin tip L2 changed its diameter when the pin L1 was pressed toward thepin tip L2. The diameter of the pin tip L2 became large only whenaligning the axes of the central through-holes of the patterned material1 and the stamper 2, and the diameter of the pin tip L2 became smallwhen disposing and pressing the patterned material 1 and the stamper 2.

In the first example, a glass substrate having the diameter of 27.4 mm,the thickness of 0.381 mm, and the central through-hole diameter of 7 mmwas used as the patterned material 1.

A quartz substrate having the diameter of 27.4 mm, the thickness of0.381 mm, and the central through-hole diameter of 7 mm was used as thestamper 2. Groove patterns each having the width of 2 μm, the pitch of 4μm, and the depth of 80 nm were formed in the range of diameter from 20to 25 mm of the stamper 2 in a concentric pattern by thephotolithography technique. The groove patterns were arrangedconcentrically relative to the central axis of the central through-holeof the stamper 2. A releasing layer containing fluorine was formed onthe surface of the stamper 2.

A resin was dropped to the surface of the patterned material 1 by thedispensing technique. The resin used in the first example was anacrylate-based resin having a photosensitive material added thereto, andprepared to have the viscosity of 4 cP (4 mPas). The resin was appliedto the surface of the patterned material 1 by a dripping device (notshown) with a single nozzle. The resin was set to be applied in a dropof 8 mL.

The resin was applied to the surface of the patterned material 1 on thecircumference at the radius of 10 mm thereof in four directions(90-degree interval).

Before the patterned material 1 and the stamper 2 were pressed againsteach other, the pressure in the pressure-reduced chamber was reduced to−80 kPa, and then stamper 2 was pressed against the patterned material 1in the pressure atmosphere of −80 kPa. Thereby, the resin applied to thesurface of the patterned material 1 spread on the patterned material 1by the weight of the stamper 2, but the resin applied at each point inthe four directions were not in contact with one another.

The stage 5 was moved up toward the upper plate 3 b, and then thepatterned material 1 and the stamper 2 were pressed against each other.The pressure load was set to be 0.25 kN. Because the lower surface ofthe patterned material 1 was in contact with the curved upper surface ofthe buffer layer 7 having the highest portion of the curved surface inthe center, the center portion of the upper surface of the patternedmaterial 1 was pressed against the stamper 2 with the highest pressure.As the stage 5 was further moved up, the pressure applied to thepatterned material 1 increased, and then the pressure distribution onthe patterned material 1 changed over time. When the pressure loadreached 0.25 kN, the pressure load was highest in the vicinity of thecircumference at the radius of 8 mm of the patterned material 1, andgradually becomes lower from an edge of the central through-hole towardthe outer circumference of the patterned material 1, so that a contourline of the pressure distribution was defined in a concentric pattern onthe patterned material 1. When the stamper 2 was pressed against thepatterned material 1, the resin applied to the surface of the patternedmaterial 1 was irradiated with an ultraviolet light UV from a lightsource (not shown) arranged above the upper plate 3 b. The resin wasirradiated with the ultraviolet light UV through the stamper 2 so thatthe resin became cured. After the resin became cured, the stage 5 wasmoved down. The patterned material 1 and the stamper 2 were transferredto a separation mechanism (not shown), and then the stamper 2 wasseparated from the patterned material 1. Accordingly, the thin filmlayer T1 (see FIG. 2D) was formed on the surface of the patternedmaterial 1, and the pattern layer T2 (see FIG. 2D) including the groovepatterns each having the width of 2 μm, the pitch of 4 μm, and the depthof 80 nm according to the fine pattern 2 a (see FIG. 2D) formed on thesurface of the stamper 2 was formed on the thin film layer T1 in aconcentric pattern.

In the first example, the thin film layer T1 formed as described abovewas measured for the film thickness distribution. Portions of thesurface of the patterned material 1 were removed in the radius directionat a 120-degree interval, and then a difference in level between thesurface of the patterned material 1 and the surface of the thin filmlayer T1 was observed in the three directions on the surface of thepatterned material 1 by the atom force microscope. In the range ofradius from 10 to 12.5 mm of the patterned material 1, the averagethickness of the thin film layer T1 was 1.9 nm and the standarddeviation (σ) of the film thickness was 1.3 nm. The thickness of thethin film layer T1 ranges from 1 to 5 nm in the range of radius from 7to 11 mm of the patterned material 1.

Second Example

The second example employs the plate 3 arranged in the imprint device A3(see FIG. 4) in the first example and having a curved surface on oneside, and in the second example the plate 3 had a spherical surfacehaving the curvature radius of 5190 mm. In the same manner as the firstexample, the thin film layer T1 (see FIG. 2D) was formed on the surfaceof the patterned material 1, and the pattern layer T2 (see FIG. 2D)including the groove patterns each having the width of 2 μm, the pitchof 4 μm, and the depth of 80 nm according to the fine pattern 2 a (seeFIG. 2D) formed on the surface of the stamper 2 was formed on the thinfilm layer T1 in a concentric pattern. In the range of radius from 10 to12.5 mm of the patterned material 1, the average thickness of the thinfilm layer T1 was 1.9 nm, and the standard deviation (σ) of the filmthickness was 1.6 nm.

Comparative Example

In a comparative example, the following observation was made of aconventional imprint device that used a plate having flat surfaces onboth sides thereof, instead of the plate 3 arranged in the imprintdevice A3 (see FIG. 4) in the first example and having a curved surfaceon one side. In the same manner as the first example, the thin filmlayer T1 (see FIG. 2D) was formed on the surface of the patternedmaterial 1, and the pattern layer T2 (see FIG. 2D) including the groovepatterns each having the width of 2 μm, the pitch of 4 μm, and the depthof 80 nm according to the fine pattern 2 a (see FIG. 2D) formed on thesurface of the stamper 2 was formed on the thin film layer T1 in aconcentric pattern. The pressure load was set to be 0.5 kN, 1 kN, and1.5 kN. In the range of radius from 10 to 12.5 mm of the patternedmaterial 1, the average thickness of the thin film layer T1 and thestandard deviation (σ) of the film thickness were determined for each ofthe above pressure loads. Table 1 shows the result of the observation.

TABLE 1 Pressure load (kN) 0.5 1 1.5 The average thickness of the thin50.6 9.3 9.5 film layer (nm) The standard deviation of the 107 17 17thickness of the thin film layer (nm)

When comparing the average thickness of the thin film layer T1 and thestandard deviation of the film thickness in the first and secondexamples with those in the comparative example, it was found that theaverage thickness and the standard deviation of the thin film layer T1in the first and second examples were lower than that in the comparativeexample, although the applied pressure load in the first and secondexamples was lower that that in the comparative example. Therefore, itwas proved that it is possible to spread the resin on the surface of thepatterned material 1 with a lower pressure load than that of theconventional technique, and form the thin film layer T1 having theuniform thickness.

Third Example

In a third example, description will be provided for a microstructuretransfer method of transferring a fine pattern 2 a of a stamper 2 to apatterned material 1 by using an imprint device A4 shown in FIG. 5. FIG.5 illustrates a configuration of an imprint device used in the thirdexample.

In the imprint device A4, as shown in FIG. 5, a plate 3 having a curvedsurface on one side was arranged on a stage 5, which was made ofstainless steel and was configured to move up and down. The plate 3 wasmade of quartz. The plate 3 was 100 mm in diameter, 20 mm in thicknessat maximum, and had a spherical surface having the curvature radius of5190 mm. A silicone rubber layer having the thickness of 0.5 mm wasdisposed on the surface of the plate 3 so as to form a buffer layer 7 onthe plate 3. On the buffer layer 7 were disposed a patterned material 1and a stamper 2 in this order. The patterned material 1 and the stamper2 were arranged such that a resin-applied surface of the patternedmaterial 1 and a pattern-formed surface of the stamper 2 face to eachother. An upper plate 3 b was arranged above the stamper 2 and held by aplate holding unit 3 c. The upper plate 3 b was made of glass.

In the third example, a quartz substrate having the diameter of 100 mmand the thickness of 1 mm was used as the patterned material 1.

A quartz substrate having the diameter of 100 mm and the thickness of0.5 mm was used as the stamper 2. Groove patterns each having the widthof 2 μm, the pitch of 4 μm, and the depth of 150 nm were formed in therange of diameter 80 mm of the stamper 2 in a concentric pattern by thephotolithography technique. A releasing layer (not shown) containingfluorine was formed on the surface of the stamper 2.

A resin was dropped to the surface of the patterned material 1 by thedispensing technique. The resin had a photosensitive material addedthereto, and was prepared to have the viscosity of 4 cP (4 mPas). Theresin was applied to the surface of the patterned material 1 by adripping device (not shown) with a single nozzle. The resin was appliedin one drop of 2 μL in the center of the patterned material 1.

Before the patterned material 1 and the stamper 2 were pressed againsteach other, the pressure in the pressure-reduced chamber was reduced to−80 kPa, and the surfaces of the patterned material 1 and the stamper 2were exposed to the lower pressure than the atmospheric pressure.

Next, the stage 5 was moved up toward the upper plate 3 b, and then thepatterned material 1 and the stamper 2 were pressed against each other.Because the lower surface of the patterned material 1 was in contactwith the curved upper surface of the buffer layer 7, having the highestportion of the curved surface in the center, the center portion of theupper surface of the patterned material 1 was pressed against thestamper 2 with the highest pressure. As the stage 5 was further movedup, the pressure applied to the patterned material 1 increased, and thenthe pressure distribution on the patterned material 1 changed over time.When the stage 5 stopped moving up, the pressure load was highest in thecenter of the patterned material 1, and gradually becomes lower towardthe outer circumference of the patterned material 1, so that a contourline of the pressure distribution was defined in a concentric pattern onthe patterned material 1. While the stamper 2 was pressed against thepatterned material 1, the resin applied to the surface of the patternedmaterial 1 was irradiated with an ultraviolet light UV from a lightsource (not shown) arranged above the upper plate 3 b. The resin wasirradiated with the ultraviolet light UV through the stamper 2 so thatthe resin became cured. After the resin became cured, the stage 5 wasmoved down. Then, the patterned material 1 and the stamper 2 weretransferred to a separation mechanism (not shown), and thereby thestamper 2 was separated from the patterned material 1. The thin filmlayer T1 (see FIG. 2D) was formed on the surface of the patternedmaterial 1, and the pattern layer T2 (see FIG. 2D) including the groovepatterns each having the width of 2 μm, the pitch of 4 μm, and the depthof 150 nm according to the fine pattern 2 a (see FIG. 2D) formed on thesurface of the stamper 2 was formed on the thin film layer T1 in aconcentric pattern.

Portions of the surface of the patterned material 1 including the thinfilm layer T1 was removed in the diameter direction, so that adifference in level between the surface of the patterned material 1 andthe surface of the thin film layer T1 was measured in the patternedregion by the atom force microscope. The average thickness of the thinfilm layer T1 was 10.3 nm and the standard deviation (σ) of the filmthickness was 9.9 nm.

Fourth Example

In a fourth example, description will be provided for a microstructuretransfer method of transferring a fine pattern 2 a of a stamper 2 to apatterned material 1 by using an imprint device A5 shown in FIG. 6. FIG.6 illustrates a configuration of an imprint device used in the fourthexample.

In the imprint device A5, as shown in FIG. 6, a plate 3 has flatsurfaces, and openings of a plurality of flow paths H are arranged infive concentric circles on the upper surface of the plate 3 in the samemanner as shown in FIG. 3B. The plurality of flow paths H in each circleis connected to pressure adjustment mechanisms B1, B2, B3, B4, and B5,respectively, which operate individually, in the same manner as shown inFIG. 3B. The pressure adjustment mechanisms B1, B2, B3, B4, and B5adjust the pressure of the nitrogen gas, so that the nitrogen gas isejected from the openings of the flow paths H arranged in the samecircle with the same pressure. A pin L1 was inserted through the centerof the stage 5 so as to align the axes of the central through-holes ofthe patterned material 1 and the stamper 2. Although not shown, a pintip L2 changes its diameter when the pin L1 is pressed toward the pintip L2. The diameter of the pin tip L2 becomes large only when aligningthe axes of the central through-holes of the patterned material 1 andthe stamper 2, and the diameter of the pin tip L2 becomes small whendisposing and pressing the patterned material 1 and the stamper 2.

In the fourth example, the patterned material 1 was disposed on theplate 3. The stamper 2 having the fine pattern 2 a was disposed on thepatterned material 1 to face a patterned surface of the patternedmaterial 1. An upper plate 3 b was held by a plate holding unit 3 c.Before the patterned material 1 and the stamper 2 were pressed againsteach other, the pressure in the pressure-reduced chamber was reduced to−80 kPa, and the surfaces of the patterned material 1 and the stamper 2were exposed to the lower pressure than the atmospheric pressure.

In the fourth example, a glass substrate having the diameter of 27.4 mm,the thickness of 0.381 mm, and the central through-hole diameter of 7 mmwas used as the patterned material 1.

A quartz substrate having the diameter of 27.4 mm, the thickness of0.381 mm, and the central through-hole diameter of 7 mm was used as thestamper 2. Groove patterns each having the width of 2 μm, the pitch of 4μm, and the depth of 80 nm were formed in the range of diameter from 20to 25 mm of the stamper 2 in a concentric pattern by thephotolithography technique. The groove patterns were arrangedconcentrically relative to the central axis of the central through-holeof the stamper 2. A releasing layer containing fluorine was formed onthe surface of the stamper 2.

A resin was dropped to the surface of the patterned material 1 by thedispensing technique. The applied resin was an acrylate-based resinhaving a photosensitive material added thereto, and prepared to have theviscosity of 4 cP (4 mPas). The resin was applied to the surface of thepatterned material 1 by a coating head, which had 512 nozzles (2 rowseach containing 256 nozzles) and ejected the resin by the piezotechnique. The nozzles of the coating head were spaced at an interval of70 μm in the row direction and 140 μm between the rows. Each of thenozzles ejected the resin of approximately 5 pL.

The positions on the patterned material 1, to which the resin isapplied, were determined depending on the spread of one drop of theresin when the stamper 2 and the patterned material 1 were pressedagainst each other. The resin was applied to the surface of thepatterned material 1 and then the stamper 2 was pressed against thepatterned material 1. Accordingly, the drop of the resin spread in anellipse, which is 140 μm in the direction perpendicular to the groovepattern (in the radius direction of the patterned material 1) and 850 μmin the direction parallel to the groove pattern (in the circumferentialdirection of the patterned material 1). As a result, a pitch of theresin to be applied on the patterned material 1 was determined to be 80μm in the radius direction and 510 μm in the circumferential directionin the range of diameter from 20 to 25 mm of the patterned material 1.

Then, the nitrogen gas was ejected from the openings of the flow paths Hon the surface of the plate 3, and thereby the back surface of thepatterned material 1 was separated from the front surface of the plate 3and the front surface of the patterned material 1 was pressed againstthe front surface of the stamper 2. The ejected nitrogen gas passedthrough a space between the front surface of the plate 3 and the backsurface of the patterned material 1, and then the nitrogen gas wasdischarge from a predetermined exhaust port (not shown). The pressureadjustment mechanisms B1, B2, B3, B4, and B5 control an amount of thenitrogen gas to be ejected, so that the pressure of the nitrogen gasejected through each flow path H was set to be 0.5 MPa, 0.5 MPa, 0.45MPa, 0.4 MPa, and 0.4 MPa in order from the inner circumference side ofthe plate 3. In this case, the applied pressure was highest on the edgeof the central through-hole of the patterned material 1, and graduallybecomes lower toward the outer circumference of the patterned material1. Thereby, a contour line of the pressure distribution is defined in aconcentric pattern on the patterned material 1.

While the patterned material 1 and the stamper 2 were pressed againsteach other, the resin applied to the patterned material 1 was irradiatedwith an ultraviolet light UV from a light source (not shown) arrangedabove the upper plate 3 b. The resin was irradiated with the ultravioletlight UV through the stamper 2 so that the resin became cured. After theresin became cured, the pressure adjustment mechanisms B1, B2, B3, B4,and B5 reduced the pressure of the ejected nitrogen gas, so that thepatterned material 1 sticks to the plate 3. Accordingly, the stamper 2was separated from the patterned material 1. The thin film layer T1 (seeFIG. 2D) was formed on the surface of the patterned material 1, and thepattern layer T2 (see FIG. 2D) including the groove patterns each havingthe width of 2 μm, the pitch of 4 μm, and the depth of 80 nm accordingto the fine pattern 2 a (see FIG. 2D) formed on the surface of thestamper 2 was formed on the thin film layer T1 in a concentric pattern.

Five pieces of the patterned material 1 were fabricated according to thefourth example of the present invention. For the five pieces of thepatterned material 1, portions of the surface of the patterned material1 including the thin film layer T1 were removed in the radius directionat a 120-degree interval, so that a difference in level between thesurface of the patterned material 1 and the surface of the thin filmlayer T1 was observed in the three directions on the surface of thepatterned material 1 by the atom force microscope. In the patternedregion of the patterned material 1, the average thickness of the thinfilm layer T1 for the five pieces was 7.5 nm and the standard deviation(σ) of the film thickness for the five pieces was 3.1 nm.

Fifth Example

An imprint device used in a fifth example had the same configuration asthat of the imprint device A5 (see FIG. 6) used in the fourth example,except that the patterned material 1 was sandwiched between upper andlower stampers 2, 2 in the fifth example. In the fifth example, the finepatterns 2 a were transferred to both surfaces of the patterned material1.

In the fifth example, the resin was applied to the surface of the lowerstamper 2 opposing the patterned material 1 and the surface of thepatterned material 1 opposing the upper stamper 2. The nitrogen gas wasejected from the lower surface side of the lower stamper 2, so that theupper and lower stampers 2, 2 were pressed against both surfaces of thepatterned material 1. Accordingly, the upper and lower stampers 2, 2were separated from both surfaces of the patterned material 1. The thinfilm layers T1, T1 (see FIG. 2D) were formed on both surfaces of thepatterned material 1. The pattern layers T2, T2 (see FIG. 2D) includingthe groove patterns each having the width of 2 μm, the pitch of 4 μm,and the depth of 80 nm according to the fine pattern 2 a (see FIG. 2D)formed on the surface of the stamper 2 were formed on the thin filmlayers T1, T1 in a concentric pattern. The thickness of each of the thinfilm layers T1, T1 formed on both surfaces of the patterned material 1was less than or equal to 20 nm.

Sixth Example

In a sixth example, the fine pattern was transferred to a substrate fora high-capacity magnetic recording medium (discrete track medium) byusing the imprint device A5 (see FIG. 6) according to the fourthexample.

In the sixth example, a glass disk substrate having the diameter of 27.4mm, the thickness of 0.381 mm, and the central through-hole diameter of7 mm was used as a patterned material 1.

A quartz substrate having the diameter of 27.4 mm, the thickness of0.381 mm, and the central through-hole diameter of 7 mm was used as astamper 2. Groove patterns each having the width of 50 nm, the depth of80 nm and the pitch of 100 nm were formed on the stamper 2 in aconcentric pattern by the conventional electron-beam direct writingtechnique. The groove patterns are arranged such that the central axesof the groove patterns correspond with the central axis of the centralthrough-hole of the stamper 2. A releasing layer containing fluorine andhaving the thickness of 3 nm was formed on the surface of the stamper 2.

A resin was dropped to the surface of the patterned material 1 by thedispensing technique. The dropped resin had a photosensitive materialadded thereto and was prepared to have the viscosity of 4 cP (4 mPas).The resin was applied to the surface of the patterned material 1 by acoating head, which had 512 nozzles (2 rows each containing 256 nozzles)and ejected the resin by the piezo technique. The nozzles of the coatinghead are spaced at an interval of 70 μm in the row direction and 140 μmbetween the rows. Each of the nozzles ejected the resin of approximately5 pL. The resin was applied on the patterned material 1 at the pitch of150 μm in the radius direction and 270 μm in the circumferentialdirection.

In the same manner as the fourth example, the thin film layer T1 (seeFIG. 2D) having the thickness of 10 nm on average was formed on thesurface of the patterned material 1, and the pattern layer T2 (see FIG.2D) including the groove patterns each having the width of 50 nm, thedepth of 80 nm, and the pitch of 100 nm according to the fine pattern 2a (see FIG. 2D) formed on the surface of the stamper 2 was formed on thethin film layer T1.

FIG. 7 is an electron microscope photograph showing a cross-sectionalsurface of the pattern formation layer T3 (see FIG. 2D) having the thinfilm layer T1 and the pattern layer T2.

Seventh Example

In a seventh example, description will be provided for a method ofmanufacturing a discrete track medium by the microstructure transfermethod according to the present invention with the drawings ifnecessary. Of the drawings to be referred to hereinafter, FIGS. 8A to 8Dillustrate a manufacturing process of a discrete track medium.

As shown in FIG. 8A, there was prepared a glass substrate 22 having apattern formation layer 21 formed thereon, as obtained in the sixthexample. The pattern formation layer 21 was made of the photo curableresin 6 and had a surface structure of the stamper 2 transferredthereto.

Next, a surface of the glass substrate 22 was processed by theconventional dry etching technique with the pattern formation layer 21as a mask. As a result, as shown in FIG. 8B, a fine-patterned portioncorresponding to the pattern of the pattern formation layer 21 wasetched on the surface of the glass substrate 22. In the seventh example,fluorine-containing gas was used for the dry etching. The dry etchingmay be performed in such a manner that a thin film portion of thepattern formation layer 21 is etched and removed by the oxygen plasmaetching, and then the exposed surface of the glass substrate 22 isetched with fluorine-containing gas.

Then, as shown in FIG. 8C, on the glass substrate 22 with thefine-patterned portion formed thereon was formed a magnetic recordingmedium formation layer 23 including a pre-coat layer, a magnetic domaincontrol layer, a soft magnetic underlayer, an intermediate layer, aperpendicular recording layer, and a protection layer by the DCmagnetron sputtering technique (for example, see Japanese Laid-openPatent Application No. 2005-038596). The magnetic domain control layerincluded a nonmagnetic layer and an antiferromagnetic layer.

Next, as shown in FIG. 8D, a nonmagnetic material 27 was applied to asurface of the magnetic recording medium formation layer 23, so that thesurface of the glass substrate 22 was flattened. As a result, a discretetrack medium M1 having approximately 200 Gbpsi in terms of area densitywas manufactured.

Eighth Example

In an eighth example, description will be provided for another exampleof a method of manufacturing a discrete track medium by themicrostructure transfer method according to the present invention withreference to the drawings if necessary. Of the drawings to be referredto hereinafter, FIGS. 9A to 9E illustrate a manufacturing process of adiscrete track medium.

In the eighth example, the below-described substrate was preparedinstead of the glass substrate 22 having the pattern formation layer 21formed thereon as obtained in the first example. As shown in FIG. 9A,the substrate was obtained such that a soft magnetic underlayer 25 wasformed on the glass substrate 22. Then, as shown in FIG. 9B, on thesubstrate was formed a pattern formation layer 21 made of the photocurable resin 6 and having the surface structure of the stamper 2transferred thereto in the same manner as the first example.

A surface of the soft magnetic under layer 25 was processed by theconventional dry etching technique with the pattern formation layer 21as a mask. As a result, as shown in FIG. 9C, a fine-patterned portioncorresponding to the pattern of the pattern formation layer 21 wasetched on the surface of the soft magnetic under layer 25. In the eighthexample, fluorine-containing gas was used for the dry etching.

Then, as shown in FIG. 9D, on the surface of the soft magneticunderlayer 25 with the fine-patterned portion formed thereon was formeda magnetic recording medium formation layer 23 including a pre-coatlayer, a magnetic domain control layer, a soft magnetic underlayer, anintermediate layer, a perpendicular recording layer, and a protectionlayer by the DC magnetron sputtering technique (for example, seeJapanese Laid-open Patent Application No. 2005-038596). The magneticdomain control layer included a nonmagnetic layer and anantiferromagnetic layer.

Next, as shown in FIG. 9E, a nonmagnetic material 27 was applied to asurface of the magnetic recording medium formation layer 23, so that thesurface of the soft magnetic under layer 25 was flattened. As a result,a discrete track medium M2 having approximately 200 Gbpsi in terms ofarea density was manufactured.

Ninth Example

In an ninth example, description will be provided for a method ofmanufacturing a disk substrate for a discrete track medium by themicrostructure transfer method according to the present invention withreference to the drawings if necessary. Of the drawings to be referredto hereinafter, FIGS. 10A to 10E illustrate a manufacturing process of adisk substrate for a discrete track medium.

As shown in FIG. 10A, a novolak resin was previously applied to asurface of a glass substrate 22 to form a flat layer 26 on the glasssubstrate 22. The flat layer 26 may be formed, for example, by thespin-coating technique or a method of pressing the resin with a plate.Then, as shown in FIG. 10B, a pattern formation layer 21 was formed onthe flat layer 26. The pattern formation layer 21 was formed by applyinga silicone resin to a surface of the flat layer 26 and using themicrostructure transfer method of the present invention.

As shown in FIG. 10C, a thin film portion of the pattern formation layer21 was etched and removed by the dry etching technique usingfluorine-containing gas. Then, as shown in FIG. 10D, an exposed portionof the flat layer 26 was etched and removed with the remaining patternformation layer 21 as a mask by the oxygen plasma etching. Then, thesurface of the glass substrate 22 was etched with thefluorine-containing gas, and the pattern formation layer 21 and the flatlayer 26 were removed. Thereby, a disk substrate M3 used for a discretetrack medium having approximately 200 Gbpsi in terms of area density wasmanufactured.

Tenth Example

In an tenth example, description will be provided for another example ofa method of manufacturing a disk substrate for a discrete track mediumby the microstructure transfer method according to the present inventionwith reference to the drawings if necessary. Of the drawings to bereferred to hereinafter, FIGS. 11A to 11E illustrate a manufacturingprocess of a disk substrate for a discrete track medium.

As shown in FIG. 11A, an acrylate resin having a photosensitive materialadded thereto was applied to a surface of a glass substrate 22, andthereby a pattern formation layer 21 was formed on the surface of theglass surface 22 according to the microstructure transfer method of thepresent invention. In the tenth example, on the glass substrate 22 wasformed the pattern formation layer 21 having a fine pattern that isreverse to a fine pattern to be formed on the glass substrate 22. Next,as shown in FIG. 11B, a resin containing a silicone and a photosensitivematerial was applied to a surface of the pattern formation layer 21 toform a flat layer 26 on the pattern formation layer 21. The flat layer26 may be formed, for example, by the spin-coating technique or a methodof pressing the resin with a plate. Then, as shown in FIG. 11C, asurface of the flat layer 26 was etched with fluorine-containing gas, sothat the upper surface of the pattern formation layer 21 was exposed. Asshown in FIG. 11D, the exposed surface of the pattern formation layer 21was etched and removed with the remaining flat layer 26 as a mask by theoxygen plasma etching, so that the upper surface of the glass substrate22 was exposed. Then, as shown in FIG. 11E, the exposed surface of theglass substrate 22 was etched with fluorine-containing gas, and thepattern formation layer 21 and the flat layer 26 were removed. Thereby,a disk substrate M4 used for a discrete track medium havingapproximately 200 Gbpsi in terms of area density was manufactured.

Eleventh Example

In an eleventh example, description will be provided for an opticalinformation processor manufactured by the microstructure transfer methodof the present invention.

The eleventh example describes a case where an optical device forchanging a traveling direction of an incident light was applied to anoptical information processor used in an optical multiplexingcommunication system.

FIG. 12 is a schematic block diagram of an optical circuit as a basiccomponent of an optical device. FIG. 13 is a schematic block diagram ofa structure of a waveguide of an optical circuit.

As shown in FIG. 12, an optical circuit 30 was formed on a substrate 31made of aluminum nitride and having the length (l) of 30 mm, the width(w) of 5 mm and the thickness of 1 mm. The optical circuit 30 includes aplurality of oscillation units 32 each having an indium phosphorus-basedsemiconductor laser and a driver circuit, waveguides 33, 33 a, andoptical connectors 34, 34 a. The semiconductor lasers are set to havedifferent oscillation wavelengths from one another by 2 to 50 nm.

In the optical circuit 30, an optical signal is input from each of theoscillation units 32, and passes through the waveguides 33 a and 33.Then, the optical signal is transmitted to the optical connector 34 viathe optical connector 34 a. The optical signals input through thewaveguides 33 a are multiplexed in the waveguide 33.

As shown in FIG. 13, a plurality of fine projections 35 is projectedlyprovided inside the waveguides 33. The waveguide 33 a has an inputsection having the width l₁ of 20 μm and having a trumpet-shape asviewed in a plane cross section, so that it is possible to allow for analignment error that occurs between the oscillation unit 32 and thewaveguide 33. In the trumpet-shaped portion of the waveguide 33 a, agroup of the fine projections 35 are provided to form patterns such thatan area in absence of the fine projections 35 becomes gradually narrowerfrom the width W₁ on the input section side, and a signal light passesalong the area in absence of the fine projections 35. The fineprojections 35 are absent in one line in the middle of the straightportion of the waveguide 33. Thereby, a region l₂ free from a photonicband gap is provided, and thereby the optical signal is guided from thetrumpet-shaped portion into the region l₂ having the width of 1 μm. Apitch between each fine projection 35 is set to be 0.5 μm. Forsimplification purposes, the number of the fine projections 35illustrated in FIG. 13 is smaller than those actually arranged.

The present invention is applied to the waveguides 33, 33 a and theoptical connector 34 a. Namely, the microstructure transfer method ofthe present invention is used for align the substrate 31 with thestamper 2 (see FIG. 1). The microstructure transfer method is utilizedfor forming the predetermined fine projections 35 in the predeterminedwaveguides 33, 33 a and the predetermined optical connector 34 a. Theoptical connector 34 a has a right and left reversed (mirror symmetry)structure of the waveguide 33 a of FIG. 13. An arrangement of the fineprojections 35 in the optical connector 34 a is mirror symmetry to thatof the fine projections 35 in the waveguide 33 a in FIG. 13.

An equivalent diameter (diameter or one side) of the fine projection 35may be arbitrarily set in the range from 10 nm to 10 μm, depending on awavelength of a light source used for a semiconductor laser. Preferably,the height of the fine projection 35 is set to be in the range from 50nm to 10 μm. A distance (pitch) between each fine projection 35 is setto be approximately half a wavelength of a concerned optical signal. Theabove-described optical circuit 30, which outputs a plurality of opticalsignals having different wavelengths in a multiplexed manner, changes alight traveling direction, so that the width (w) (see FIG. 12) of theoptical circuit 30 is reduced to 5 mm. Thereby, the optical device isreduced in size. In addition, according to the microstructure transfermethod, the fine projections 35 is formed by transferring a surfacestructure of the stamper 2 (for example, see FIG. 1), and therefore itis possible to reduce manufacturing cost of the optical circuit 30.

The eleventh example describes the case where the present invention isapplied to the optical device for multiplexing incident lights, but thepresent invention may be employed in any optical devices for controllinga light path.

Twelfth Example

In a twelfth example, description will be provided for a method ofmanufacturing a multilayer interconnection substrate by themicrostructure transfer method according to the present invention. FIGS.14A to 14L illustrate a process of manufacturing a multilayerinterconnection substrate.

As shown in FIG. 14A, a resist 52 is formed on a surface of a multilayerinterconnection substrate 61 including a silicon oxide film 62 andcopper interconnections 63, and then a pattern of a stamper 2 (notshown) is transferred to the resist 52. The alignment of the stamper 2and the substrate 61 is performed before the pattern of the stamper 2 istransferred to the resist 52, so that a desired interconnection patternis transferred to a desired position of the substrate 61.

An exposed region 53 of the multilayer interconnection substrate 61 isdry-etched with CF₄/H₂ gas, so that grooves are formed on the exposedregion 53 on the surface of the multilayer interconnection substrate 61,as shown in FIG. 14B. Next, the resist 52 is processed by RIE (ReactiveIon Etching). The resist 52 is etched until the resist 52 at a lowerstep is removed, and thereby the exposed region 53 of the multilayerinterconnection substrate 61 becomes enlarged around the remainingresist 52, as shown in FIG. 14C. Then, the exposed region 53 is furtherprocessed by the dry etching, so that the grooves already formed on theexposed region 53 as illustrated in FIG. 14B are etched deeper enough toreach the copper interconnections 63, as shown in FIG. 14D.

Next, as shown in FIG. 14E, the remaining resist 52 is removed so thatthe multilayer interconnection substrate 61 having the grooves on thesurface thereof is fabricated. Then, a metal film (not shown) is formedon the surface of the multilayer interconnection substrate 61, and thena metal plated film 64 is formed on the resultant film by theelectrolytic plating, as shown in FIG. 14F. Then, the metal plated film64 is polished until the silicon oxide film 62 of the multilayerinterconnection substrate 61 is exposed. As a result, as shown in FIG.14G, the multilayer interconnection substrate 61 having metalinterconnections of the metal plated film 64 on the surface thereof isfabricated.

Herein, description will be provided for another process ofmanufacturing the multilayer interconnection substrate 61.

The exposed region 53 as shown in FIG. 14A is processed by the dryetching until the exposed region 53 is etched deeper enough to reach thecopper interconnections 63 inside the multilayer interconnectionsubstrate 61, as shown in FIG. 14H. Next, the resist 52 is processed byRIE (Reactive Ion Etching), and as shown in FIG. 14I, the resist 52 atthe lower step is removed. Then, a metal film 65 is formed on a surfaceof the multilayer interconnection substrate 61 by the sputteringtechnique, as shown in FIG. 14J. Then, the remaining resist 52 isremoved by the lift-off technique, and thereby the metal film 65partially remains on the surface of the multilayer interconnectionsubstrate 61, as shown in FIG. 14K. Next, the partially remaining metalfilm 65 is subjected to nonelectrolytic plating, and thereby themultilayer interconnection substrate 61 having metal interconnections ofthe metal plated film 64 on the surface thereof is fabricated. Asdescribed above, the present invention may be applied to a manufacturingmethod of the multilayer interconnection substrate 61 so that it ispossible to form metal interconnections with high dimensional precision.

1. A microstructure transfer method comprising a step of contacting astamper having a fine pattern thereon with a material, and a step oftransferring the fine pattern of the stamper to the material by pressingthe stamper against the material, so as to form a patterned material, inthe step of transferring, a nonuniform pressure distribution beingprovided in a patterned region of the patterned material.
 2. Amicrostructure transfer method according to claim 1, wherein thepressure distribution has the highest pressure point in the patternedregion.
 3. The microstructure transfer method according to claim 1,wherein the pressure distribution defines a contour line of the highestpressure point in the patterned region, and the contour line defines aclosed region in the patterned region.
 4. The microstructure transfermethod according to claim 1, wherein the pressure distribution changesin the patterned region over time.
 5. The microstructure transfer methodaccording to claim 1 further comprising, a step of pressing one of afirst plate provided on one side of the stamper and a second plateprovided on one side of the material against the other.
 6. Themicrostructure transfer method according to claim 1 further comprising,a step of applying a material on at least one of surfaces of thematerial and the stamper so as to form a pattern formation layer havingthe fine pattern, before the stamper is pressed against the material,the pattern formation layer being formed by spreading the appliedmaterial on the surface of the material when the stamper and thematerial are in contact with each other.